Posttraumatic Stress Disorder (PTSD), which occurs in at least 15-20% of individuals exposed to a traumatic event, is a chronic condition associated with the development of a multitude of negative physical and mental health consequences and the co-occurrence of Major Depressive Disorder (MDD). Sleep disturbances, and especially nightmares and insomnia, are quite common in patients with PTSD, but the standard treatments for PTSD do not directly focus on sleep problems. Perhaps as a result, sleep disturbances are one of the most common residual symptoms following both PTSD treatments and depression treatments. Importantly, insomnia, depression and PTSD are each characterized by similar biological dysregulation, including alterations in important aspects of sleep (rapid eye movement sleep and slow wave sleep) as well as processes linked to health and disease (stress system responses and inflammatory processes).